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<FONT color="green">001</FONT>    <a name="line.1"></a>
<FONT color="green">002</FONT>    /*<a name="line.2"></a>
<FONT color="green">003</FONT>     * Copyright (C) 2011 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<FONT color="green">004</FONT>     *<a name="line.4"></a>
<FONT color="green">005</FONT>     * $Id: StringEncoder.html 101 2011-05-10 16:43:38Z archie.cobbs $<a name="line.5"></a>
<FONT color="green">006</FONT>     */<a name="line.6"></a>
<FONT color="green">007</FONT>    <a name="line.7"></a>
<FONT color="green">008</FONT>    package org.dellroad.stuff.string;<a name="line.8"></a>
<FONT color="green">009</FONT>    <a name="line.9"></a>
<FONT color="green">010</FONT>    import java.util.regex.Matcher;<a name="line.10"></a>
<FONT color="green">011</FONT>    import java.util.regex.Pattern;<a name="line.11"></a>
<FONT color="green">012</FONT>    <a name="line.12"></a>
<FONT color="green">013</FONT>    /**<a name="line.13"></a>
<FONT color="green">014</FONT>     * Encodes/decodes Java strings, escaping control and XML-invalid characters.<a name="line.14"></a>
<FONT color="green">015</FONT>     */<a name="line.15"></a>
<FONT color="green">016</FONT>    public final class StringEncoder {<a name="line.16"></a>
<FONT color="green">017</FONT>    <a name="line.17"></a>
<FONT color="green">018</FONT>        private static final char[] HEXDIGITS = "0123456789abcdef".toCharArray();<a name="line.18"></a>
<FONT color="green">019</FONT>    <a name="line.19"></a>
<FONT color="green">020</FONT>        private StringEncoder() {<a name="line.20"></a>
<FONT color="green">021</FONT>        }<a name="line.21"></a>
<FONT color="green">022</FONT>    <a name="line.22"></a>
<FONT color="green">023</FONT>        /**<a name="line.23"></a>
<FONT color="green">024</FONT>         * Encode a string, escaping control and XML-invalid characters.<a name="line.24"></a>
<FONT color="green">025</FONT>         * Whether tab, newline, and carriage return are escaped is optional;<a name="line.25"></a>
<FONT color="green">026</FONT>         * these are the three control characters that are valid inside XML documents.<a name="line.26"></a>
<FONT color="green">027</FONT>         * &lt;p/&gt;<a name="line.27"></a>
<FONT color="green">028</FONT>         * &lt;p/&gt;<a name="line.28"></a>
<FONT color="green">029</FONT>         * Characters are escaped using &lt;code&gt;&amp;#92;uNNNN&lt;/code&gt; notation like Java unicode characters,<a name="line.29"></a>
<FONT color="green">030</FONT>         * e.g., &lt;code&gt;0x001f&lt;/code&gt; would appear in the encoded string as &lt;code&gt;&amp;#92;u001f&lt;/code&gt;.<a name="line.30"></a>
<FONT color="green">031</FONT>         * Normal Java backslash escapes are used for tab, newline, carriage return, backspace, and formfeed.<a name="line.31"></a>
<FONT color="green">032</FONT>         * Backslash characters are themselves encoded with a double backslash.<a name="line.32"></a>
<FONT color="green">033</FONT>         *<a name="line.33"></a>
<FONT color="green">034</FONT>         * @param value         string to encode (possibly null)<a name="line.34"></a>
<FONT color="green">035</FONT>         * @param escapeTABNLCR escape tab, newline, and carriage return characters as well<a name="line.35"></a>
<FONT color="green">036</FONT>         * @return the encoded version of {@code value}, or {@code null} if {@code value} was {@code null}<a name="line.36"></a>
<FONT color="green">037</FONT>         * @see #decode<a name="line.37"></a>
<FONT color="green">038</FONT>         * @see #isValidXMLChar<a name="line.38"></a>
<FONT color="green">039</FONT>         */<a name="line.39"></a>
<FONT color="green">040</FONT>        public static String encode(String value, boolean escapeTABNLCR) {<a name="line.40"></a>
<FONT color="green">041</FONT>            if (value == null)<a name="line.41"></a>
<FONT color="green">042</FONT>                return value;<a name="line.42"></a>
<FONT color="green">043</FONT>            StringBuilder buf = new StringBuilder(value.length() + 4);<a name="line.43"></a>
<FONT color="green">044</FONT>            final int limit = value.length();<a name="line.44"></a>
<FONT color="green">045</FONT>            for (int i = 0; i &lt; limit; i++) {<a name="line.45"></a>
<FONT color="green">046</FONT>                final char ch = value.charAt(i);<a name="line.46"></a>
<FONT color="green">047</FONT>    <a name="line.47"></a>
<FONT color="green">048</FONT>                // Handle special escapes<a name="line.48"></a>
<FONT color="green">049</FONT>                switch (ch) {<a name="line.49"></a>
<FONT color="green">050</FONT>                    case '\\':<a name="line.50"></a>
<FONT color="green">051</FONT>                        buf.append('\\').append('\\');<a name="line.51"></a>
<FONT color="green">052</FONT>                        continue;<a name="line.52"></a>
<FONT color="green">053</FONT>                    case '\b':<a name="line.53"></a>
<FONT color="green">054</FONT>                        buf.append('\\').append('b');<a name="line.54"></a>
<FONT color="green">055</FONT>                        continue;<a name="line.55"></a>
<FONT color="green">056</FONT>                    case '\f':<a name="line.56"></a>
<FONT color="green">057</FONT>                        buf.append('\\').append('f');<a name="line.57"></a>
<FONT color="green">058</FONT>                        continue;<a name="line.58"></a>
<FONT color="green">059</FONT>                    case '\t':<a name="line.59"></a>
<FONT color="green">060</FONT>                        if (escapeTABNLCR) {<a name="line.60"></a>
<FONT color="green">061</FONT>                            buf.append('\\').append('t');<a name="line.61"></a>
<FONT color="green">062</FONT>                            continue;<a name="line.62"></a>
<FONT color="green">063</FONT>                        }<a name="line.63"></a>
<FONT color="green">064</FONT>                        break;<a name="line.64"></a>
<FONT color="green">065</FONT>                    case '\n':<a name="line.65"></a>
<FONT color="green">066</FONT>                        if (escapeTABNLCR) {<a name="line.66"></a>
<FONT color="green">067</FONT>                            buf.append('\\').append('n');<a name="line.67"></a>
<FONT color="green">068</FONT>                            continue;<a name="line.68"></a>
<FONT color="green">069</FONT>                        }<a name="line.69"></a>
<FONT color="green">070</FONT>                        break;<a name="line.70"></a>
<FONT color="green">071</FONT>                    case '\r':<a name="line.71"></a>
<FONT color="green">072</FONT>                        if (escapeTABNLCR) {<a name="line.72"></a>
<FONT color="green">073</FONT>                            buf.append('\\').append('r');<a name="line.73"></a>
<FONT color="green">074</FONT>                            continue;<a name="line.74"></a>
<FONT color="green">075</FONT>                        }<a name="line.75"></a>
<FONT color="green">076</FONT>                        break;<a name="line.76"></a>
<FONT color="green">077</FONT>                    default:<a name="line.77"></a>
<FONT color="green">078</FONT>                        break;<a name="line.78"></a>
<FONT color="green">079</FONT>                }<a name="line.79"></a>
<FONT color="green">080</FONT>    <a name="line.80"></a>
<FONT color="green">081</FONT>                // If character is an otherwise valid XML character, pass it through unchanged<a name="line.81"></a>
<FONT color="green">082</FONT>                if (isValidXMLChar(ch)) {<a name="line.82"></a>
<FONT color="green">083</FONT>                    buf.append(ch);<a name="line.83"></a>
<FONT color="green">084</FONT>                    continue;<a name="line.84"></a>
<FONT color="green">085</FONT>                }<a name="line.85"></a>
<FONT color="green">086</FONT>    <a name="line.86"></a>
<FONT color="green">087</FONT>                // Escape it using 4 digit hex<a name="line.87"></a>
<FONT color="green">088</FONT>                buf.append('\\');<a name="line.88"></a>
<FONT color="green">089</FONT>                buf.append('u');<a name="line.89"></a>
<FONT color="green">090</FONT>                for (int shift = 12; shift &gt;= 0; shift -= 4)<a name="line.90"></a>
<FONT color="green">091</FONT>                    buf.append(HEXDIGITS[(ch &gt;&gt; shift) &amp; 0x0f]);<a name="line.91"></a>
<FONT color="green">092</FONT>            }<a name="line.92"></a>
<FONT color="green">093</FONT>            return buf.toString();<a name="line.93"></a>
<FONT color="green">094</FONT>        }<a name="line.94"></a>
<FONT color="green">095</FONT>    <a name="line.95"></a>
<FONT color="green">096</FONT>        /**<a name="line.96"></a>
<FONT color="green">097</FONT>         * Decode a string encoded by {@link #encode}.<a name="line.97"></a>
<FONT color="green">098</FONT>         * &lt;p/&gt;<a name="line.98"></a>
<FONT color="green">099</FONT>         * &lt;p/&gt;<a name="line.99"></a>
<FONT color="green">100</FONT>         * The parsing is strict; any ill-formed backslash escape sequence (i.e., not of the form<a name="line.100"></a>
<FONT color="green">101</FONT>         * &lt;code&gt;&amp;#92;uNNNN&lt;/code&gt;, &lt;code&gt;\b&lt;/code&gt;, &lt;code&gt;\t&lt;/code&gt;, &lt;code&gt;\n&lt;/code&gt;, &lt;code&gt;\f&lt;/code&gt;, &lt;code&gt;\r&lt;/code&gt;<a name="line.101"></a>
<FONT color="green">102</FONT>         * or &lt;code&gt;\\&lt;/code&gt;) will cause an exception to be thrown.<a name="line.102"></a>
<FONT color="green">103</FONT>         *<a name="line.103"></a>
<FONT color="green">104</FONT>         * @param text string to decode (possibly null)<a name="line.104"></a>
<FONT color="green">105</FONT>         * @return the decoded version of {@code text}, or {@code null} if {@code text} was {@code null}<a name="line.105"></a>
<FONT color="green">106</FONT>         * @throws IllegalArgumentException if {@code text} contains an invalid escape sequence<a name="line.106"></a>
<FONT color="green">107</FONT>         * @see #encode<a name="line.107"></a>
<FONT color="green">108</FONT>         */<a name="line.108"></a>
<FONT color="green">109</FONT>        public static String decode(String text) {<a name="line.109"></a>
<FONT color="green">110</FONT>            if (text == null)<a name="line.110"></a>
<FONT color="green">111</FONT>                return null;<a name="line.111"></a>
<FONT color="green">112</FONT>            StringBuilder buf = new StringBuilder(text.length());<a name="line.112"></a>
<FONT color="green">113</FONT>            final int limit = text.length();<a name="line.113"></a>
<FONT color="green">114</FONT>            for (int i = 0; i &lt; limit; i++) {<a name="line.114"></a>
<FONT color="green">115</FONT>                char ch = text.charAt(i);<a name="line.115"></a>
<FONT color="green">116</FONT>    <a name="line.116"></a>
<FONT color="green">117</FONT>                // Handle unescaped characters<a name="line.117"></a>
<FONT color="green">118</FONT>                if (ch != '\\') {<a name="line.118"></a>
<FONT color="green">119</FONT>                    buf.append(ch);<a name="line.119"></a>
<FONT color="green">120</FONT>                    continue;<a name="line.120"></a>
<FONT color="green">121</FONT>                }<a name="line.121"></a>
<FONT color="green">122</FONT>    <a name="line.122"></a>
<FONT color="green">123</FONT>                // Get next char<a name="line.123"></a>
<FONT color="green">124</FONT>                if (++i &gt;= limit)<a name="line.124"></a>
<FONT color="green">125</FONT>                    throw new IllegalArgumentException("illegal trailing '\\' in encoded string");<a name="line.125"></a>
<FONT color="green">126</FONT>                ch = text.charAt(i);<a name="line.126"></a>
<FONT color="green">127</FONT>    <a name="line.127"></a>
<FONT color="green">128</FONT>                // Check for special escapes<a name="line.128"></a>
<FONT color="green">129</FONT>                switch (ch) {<a name="line.129"></a>
<FONT color="green">130</FONT>                    case '\\':<a name="line.130"></a>
<FONT color="green">131</FONT>                        buf.append('\\');<a name="line.131"></a>
<FONT color="green">132</FONT>                        continue;<a name="line.132"></a>
<FONT color="green">133</FONT>                    case 'b':<a name="line.133"></a>
<FONT color="green">134</FONT>                        buf.append('\b');<a name="line.134"></a>
<FONT color="green">135</FONT>                        continue;<a name="line.135"></a>
<FONT color="green">136</FONT>                    case 't':<a name="line.136"></a>
<FONT color="green">137</FONT>                        buf.append('\t');<a name="line.137"></a>
<FONT color="green">138</FONT>                        continue;<a name="line.138"></a>
<FONT color="green">139</FONT>                    case 'n':<a name="line.139"></a>
<FONT color="green">140</FONT>                        buf.append('\n');<a name="line.140"></a>
<FONT color="green">141</FONT>                        continue;<a name="line.141"></a>
<FONT color="green">142</FONT>                    case 'f':<a name="line.142"></a>
<FONT color="green">143</FONT>                        buf.append('\f');<a name="line.143"></a>
<FONT color="green">144</FONT>                        continue;<a name="line.144"></a>
<FONT color="green">145</FONT>                    case 'r':<a name="line.145"></a>
<FONT color="green">146</FONT>                        buf.append('\r');<a name="line.146"></a>
<FONT color="green">147</FONT>                        continue;<a name="line.147"></a>
<FONT color="green">148</FONT>                    default:<a name="line.148"></a>
<FONT color="green">149</FONT>                        break;<a name="line.149"></a>
<FONT color="green">150</FONT>                }<a name="line.150"></a>
<FONT color="green">151</FONT>    <a name="line.151"></a>
<FONT color="green">152</FONT>                // Must be unicode escape<a name="line.152"></a>
<FONT color="green">153</FONT>                if (ch != 'u')<a name="line.153"></a>
<FONT color="green">154</FONT>                    throw new IllegalArgumentException("illegal escape sequence '\\" + ch + "' in encoded string");<a name="line.154"></a>
<FONT color="green">155</FONT>    <a name="line.155"></a>
<FONT color="green">156</FONT>                // Decode hex value<a name="line.156"></a>
<FONT color="green">157</FONT>                int value = 0;<a name="line.157"></a>
<FONT color="green">158</FONT>                for (int j = 0; j &lt; 4; j++) {<a name="line.158"></a>
<FONT color="green">159</FONT>                    if (++i &gt;= limit)<a name="line.159"></a>
<FONT color="green">160</FONT>                        throw new IllegalArgumentException("illegal truncated '\\u' escape sequence in encoded string");<a name="line.160"></a>
<FONT color="green">161</FONT>                    int nibble = Character.digit(text.charAt(i), 16);<a name="line.161"></a>
<FONT color="green">162</FONT>                    if (nibble == -1) {<a name="line.162"></a>
<FONT color="green">163</FONT>                        throw new IllegalArgumentException(<a name="line.163"></a>
<FONT color="green">164</FONT>                          "illegal escape sequence '" + text.substring(i - j - 2, i - j + 4) + "' in encoded string");<a name="line.164"></a>
<FONT color="green">165</FONT>                    }<a name="line.165"></a>
<FONT color="green">166</FONT>                    assert nibble &gt;= 0 &amp;&amp; nibble &lt;= 0xf;<a name="line.166"></a>
<FONT color="green">167</FONT>                    value = (value &lt;&lt; 4) | nibble;<a name="line.167"></a>
<FONT color="green">168</FONT>                }<a name="line.168"></a>
<FONT color="green">169</FONT>    <a name="line.169"></a>
<FONT color="green">170</FONT>                // Append decodec character<a name="line.170"></a>
<FONT color="green">171</FONT>                buf.append((char)value);<a name="line.171"></a>
<FONT color="green">172</FONT>            }<a name="line.172"></a>
<FONT color="green">173</FONT>            return buf.toString();<a name="line.173"></a>
<FONT color="green">174</FONT>        }<a name="line.174"></a>
<FONT color="green">175</FONT>    <a name="line.175"></a>
<FONT color="green">176</FONT>        /**<a name="line.176"></a>
<FONT color="green">177</FONT>         * Enquote a string. Functions like {@link #encode encode(string, true)} but in addition the resulting<a name="line.177"></a>
<FONT color="green">178</FONT>         * string is surrounded by double quotes and double quotes in the string are backslash-escaped.<a name="line.178"></a>
<FONT color="green">179</FONT>         * &lt;p/&gt;<a name="line.179"></a>
<FONT color="green">180</FONT>         * &lt;p&gt;<a name="line.180"></a>
<FONT color="green">181</FONT>         * Note: the strings returned by this method are not suitable for decoding by {@link #decode}.<a name="line.181"></a>
<FONT color="green">182</FONT>         * Use {@link #dequote} instead.<a name="line.182"></a>
<FONT color="green">183</FONT>         * &lt;/p&gt;<a name="line.183"></a>
<FONT color="green">184</FONT>         */<a name="line.184"></a>
<FONT color="green">185</FONT>        public static String enquote(String string) {<a name="line.185"></a>
<FONT color="green">186</FONT>            return '"' + encode(string, true).replaceAll(Pattern.quote("\""), Matcher.quoteReplacement("\\\"")) + '"';<a name="line.186"></a>
<FONT color="green">187</FONT>        }<a name="line.187"></a>
<FONT color="green">188</FONT>    <a name="line.188"></a>
<FONT color="green">189</FONT>        /**<a name="line.189"></a>
<FONT color="green">190</FONT>         * Enquote bytes, treating them as an ASCII string.<a name="line.190"></a>
<FONT color="green">191</FONT>         *<a name="line.191"></a>
<FONT color="green">192</FONT>         * @see #enquote(String)<a name="line.192"></a>
<FONT color="green">193</FONT>         */<a name="line.193"></a>
<FONT color="green">194</FONT>        public static String enquote(byte[] data, int off, int len) {<a name="line.194"></a>
<FONT color="green">195</FONT>            char[] chars = new char[len];<a name="line.195"></a>
<FONT color="green">196</FONT>            for (int i = 0; i &lt; len; i++)<a name="line.196"></a>
<FONT color="green">197</FONT>                chars[i] = (char)(data[i] &amp; 0xff);<a name="line.197"></a>
<FONT color="green">198</FONT>            return enquote(new String(chars));<a name="line.198"></a>
<FONT color="green">199</FONT>        }<a name="line.199"></a>
<FONT color="green">200</FONT>    <a name="line.200"></a>
<FONT color="green">201</FONT>        /**<a name="line.201"></a>
<FONT color="green">202</FONT>         * Dequote a string previously enquoted by {@link #enquote}.<a name="line.202"></a>
<FONT color="green">203</FONT>         *<a name="line.203"></a>
<FONT color="green">204</FONT>         * @param quotedString a string returned by {@link #enquote}<a name="line.204"></a>
<FONT color="green">205</FONT>         * @throws IllegalArgumentException if {@code quotedString} has an invalid format (i.e., it could not have<a name="line.205"></a>
<FONT color="green">206</FONT>         *  ever been returned by {@link #enquote})<a name="line.206"></a>
<FONT color="green">207</FONT>         */<a name="line.207"></a>
<FONT color="green">208</FONT>        public static String dequote(String quotedString) {<a name="line.208"></a>
<FONT color="green">209</FONT>            int len = quotedString.length();<a name="line.209"></a>
<FONT color="green">210</FONT>            if (len == 0 || quotedString.charAt(0) != '"' || quotedString.charAt(len - 1) != '"')<a name="line.210"></a>
<FONT color="green">211</FONT>                throw new IllegalArgumentException("invalid quoted string: not surrounded by quote characters");<a name="line.211"></a>
<FONT color="green">212</FONT>            quotedString = quotedString.substring(1, len - 1);<a name="line.212"></a>
<FONT color="green">213</FONT>            if (quotedString.matches("^(\"|.*[^\\\\]\").*$"))<a name="line.213"></a>
<FONT color="green">214</FONT>                throw new IllegalArgumentException("invalid quoted string: unescaped nested quote character");<a name="line.214"></a>
<FONT color="green">215</FONT>            quotedString = quotedString.replaceAll(Pattern.quote("\\\""), Matcher.quoteReplacement("\""));<a name="line.215"></a>
<FONT color="green">216</FONT>            return decode(quotedString);<a name="line.216"></a>
<FONT color="green">217</FONT>        }<a name="line.217"></a>
<FONT color="green">218</FONT>    <a name="line.218"></a>
<FONT color="green">219</FONT>        /**<a name="line.219"></a>
<FONT color="green">220</FONT>         * Determine the length of a string previously enquoted by {@link #enquote} when it appears<a name="line.220"></a>
<FONT color="green">221</FONT>         * as the prefix of a longer string. This method assumes that the prefix is a valid quoted<a name="line.221"></a>
<FONT color="green">222</FONT>         * string; use {@link #dequote} to verify.<a name="line.222"></a>
<FONT color="green">223</FONT>         *<a name="line.223"></a>
<FONT color="green">224</FONT>         * @param string a string containing a prefix returned by {@link #enquote}<a name="line.224"></a>
<FONT color="green">225</FONT>         * @throws IllegalArgumentException if a starting or terminating quote character is not found<a name="line.225"></a>
<FONT color="green">226</FONT>         */<a name="line.226"></a>
<FONT color="green">227</FONT>        public static int enquotedLength(String string) {<a name="line.227"></a>
<FONT color="green">228</FONT>            int len = string.length();<a name="line.228"></a>
<FONT color="green">229</FONT>            if (len == 0 || string.charAt(0) != '"')<a name="line.229"></a>
<FONT color="green">230</FONT>                throw new IllegalArgumentException("invalid quoted string prefix: string does not begin with a quote character");<a name="line.230"></a>
<FONT color="green">231</FONT>            for (int i = 1; i &lt; len; i++) {<a name="line.231"></a>
<FONT color="green">232</FONT>                if (string.charAt(i) == '"' &amp;&amp; string.charAt(i - 1) != '\\')<a name="line.232"></a>
<FONT color="green">233</FONT>                    return i + 1;<a name="line.233"></a>
<FONT color="green">234</FONT>            }<a name="line.234"></a>
<FONT color="green">235</FONT>            throw new IllegalArgumentException("invalid quoted string prefix: no terminating quote character found");<a name="line.235"></a>
<FONT color="green">236</FONT>        }<a name="line.236"></a>
<FONT color="green">237</FONT>    <a name="line.237"></a>
<FONT color="green">238</FONT>        /**<a name="line.238"></a>
<FONT color="green">239</FONT>         * Determine if the given character is a valid XML character according to the XML 1.0 specification.<a name="line.239"></a>
<FONT color="green">240</FONT>         * &lt;p/&gt;<a name="line.240"></a>
<FONT color="green">241</FONT>         * &lt;p&gt;<a name="line.241"></a>
<FONT color="green">242</FONT>         * Valid characters are tab, newline, carriage return, and characters in the ranges<a name="line.242"></a>
<FONT color="green">243</FONT>         * &lt;code&gt;&amp;#92;u0020 - &amp;#92;ud7ff&lt;/code&gt; and &lt;code&gt;&amp;#92;ue000 - &amp;#92;fffdf&lt;/code&gt; (inclusive).<a name="line.243"></a>
<FONT color="green">244</FONT>         * &lt;/p&gt;<a name="line.244"></a>
<FONT color="green">245</FONT>         *<a name="line.245"></a>
<FONT color="green">246</FONT>         * @see &lt;a href="http://www.w3.org/TR/REC-xml/#charsets"&gt;The XML 1.0 Specification&lt;/a&gt;<a name="line.246"></a>
<FONT color="green">247</FONT>         */<a name="line.247"></a>
<FONT color="green">248</FONT>        public static boolean isValidXMLChar(char ch) {<a name="line.248"></a>
<FONT color="green">249</FONT>            return (ch &gt;= '\u0020' &amp;&amp; ch &lt;= '\ud7ff') || ch == '\n' || ch == '\r' || ch == '\t' || (ch &gt;= '\ue000' &amp;&amp; ch &lt;= '\ufffd');<a name="line.249"></a>
<FONT color="green">250</FONT>        }<a name="line.250"></a>
<FONT color="green">251</FONT>    }<a name="line.251"></a>
<FONT color="green">252</FONT>    <a name="line.252"></a>




























































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